1) Field of the Invention
The present invention relates to a neutralizer which is effective for neutralization of bacterial enterotoxins produced by bacteria such as Vibrio cholerae, pathogenic Escherichia coli and Salmonella.
2) Description of the Related Art
Food poisoning due to Vibrio cholerae causes severe diarrhea accompanied by abdominal pain. Consequently, patients infected with Vibrio cholerae are suffered from extreme dehydration due to the diarrhea and, in the worst case, die due to the dehydration. It is well known that the severe diarrhea observed in the case of food poisoning due to vibrio cholerae is caused by an enterotoxin called cholera toxin which Vibrio cholerae produces extracellularly. The cholera toxin is a protein with a molecular weight of 84,000 consisting of one A-subunit and five B-subunits. It is said that, among them, B-subunits bind to receptors located on a mucous cell of the small intestine, while the A component invades into the cell and increases the amount of cyclic-AMP within the cell, causing change in membrane permeability, which induces exudation of intracellular fluid and salts outside the cell and thus causes diarrhea. This kind of toxins are isolated also from pathogenic E. coli and Salmonella, and are believed to be largely responsible for causing food poisoning.
The receptors which are present on the mucous cells of the small intestine has been confirmed to be liposaccharides; gangliosides such as G.sub.M1 are identified as receptors for the cholera toxin. The utilization of this G.sub.M1 as a cholera toxin neutralizer has already been attempted. For example, Japanese Patent Publication No. 500138/1981 disclosed a technique in which gangliosides such as G.sub.M1 possessing a potent ability of neutralizing the cholera toxin were immobilized on latex or the like and used as neutralizing agents. Furthermore, Japanese Patent Laid-Open No. 72819/1980 disclosed a technique in which fat globule membranes in cow's milk were treated by heat and used as a toxin neutralizer without extracting gangliosides, G.sub.D3, G.sub.M2 and G.sub.M3, contained in the fat globular membranes.
However, at the present time G.sub.M1 is known to be available only in a minute amount, for example, in the bovine brain. Therefore, it was difficult to supply such G.sub.M1 at a low cost in a large amount. Furthermore, the methods of using milk fat globular membranes in cow's milk or the like have disadvantages such that concentrations of the resulting gangliosides, which are effective components in the milk globular membranes are not consistent, and their compositions are not stable.